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•  Transcription is the synthesis of mRNA copied from the DNA base sequence by RNA polymerase

Transcription is the process by which an RNA sequence is produced from a DNA template

  • RNA polymerase separates the DNA strands and synthesises a complementary RNA copy from one of the DNA strands
  • When the DNA strands are separated, ribonucleoside triphosphates align opposite their exposed complementary base partner
  • RNA polymerase removes the additional phosphate groups and uses the energy from this cleavage to covalently join the nucleotide to the growing sequence
  • Once the RNA sequence has been synthesised, RNA polymerase detaches from the DNA molecule and the double helix reforms

The Role of RNA Polymerase in Transcription



The sequence of DNA that is transcribed into RNA is called a gene

  • The strand that is transcribed is called the antisense strand and is complementary to the RNA sequence 
  • The strand that is not transcribed is called the sense strand and is identical to the RNA sequence (with T instead of U)

Transcription of genes occur in the nucleus (where DNA is), before the RNA moves to the cytoplasm (for translation)

Overview of Transcription